1. Field of the Invention
The present invention relates to a communication apparatus, and particularly relates to a communication apparatus wherein information signals containing ID (Identification) code are transmitted from a portable transmitter, and a controlled device is controlled in the event that the ID code within the information signals received with a receiver match a registered reference code, wherein the ID code of the portable transmitter is registered by the user.
2. Description of the Related Art
Keyless entry devices for automobiles are known as an example of communication apparatuses comprising a portable transmitter and a receiver, wherein upon transmitting of information signals containing ID code by operating the operating unit of the portable transmitter, the ID code is extracted from the information signals received at the receiver side, and wherein the controlled device can be controlled in the event that that ID code matches the reference code already registered thereto.
With such keyless entry devices, each user carries the portable transmitter, and the receiver is installed in the vehicle.
FIG. 9 is a block diagram illustrating an example of the configuration of a portable transmitter used with a known keyless entry device, and FIG. 10 is a block diagram illustrating an example of the configuration of a receiver used with a known keyless entry device.
As shown in FIG. 9, the portable transmitter 70 is provided with an operating switch unit 71 having one or more operating switches, a function code converting unit 72, a transmitting code converting unit 73, an ID code storing unit 74, a transmitting unit 75, and a transmitting antenna 76. These components 71 through 76 are connected as shown in FIG. 9.
Also, the receiver 80 is provided with a receiving unit 81, a signal processing unit 82, a reference code storing unit 83, a function code storing unit 84, a control signal generating unit 85 which is built into the signal processing unit 82, an automobile ignition key 86, and a receiving antenna 87, wherein the signal processing unit 82 and the control signal generating unit 85 are built into the control unit (CPU), and the reference code storing unit 83 and function code storing unit 84 are built into the EEPROM. These components 81 through 87 are connected as shown in FIG. 10.
The portable transmitter 70 and the receiver 80 with the above configurations each operate as described next.
First, with regard to the portable transmitter 70, the operating switch unit 71 generates various types of switch information for performing operations of controlled mechanisms of the vehicle, for example, locking or unlocking the doors, opening the trunk, and so forth, by the user operating desired operating switches. The function code converting unit 72 converts the switch information output from the operating switch unit 71 into function code corresponding to the information contents thereof. The ID code storing unit 74 stores ID code unique to each portable transmitter 70. The transmitting code converting unit 73 forms a transmitting code wherein a header code and an end code and the like are added to the function code output from the function code converting unit 72 and the ID code read out from the ID code storing unit 74. The transmitting unit 75 converts the transmitting code formed by the transmitting code converting unit 73 into transmitting signals carried by electromagnetic waves or the like, and transmits the transmitting signals through the transmitting antenna 76.
On the other hand, with regard to the receiver 80, the receiving unit 81 receives the transmitting signals through the receiving antenna 87, and restores the transmitting code. The signal processing unit 82 compares the ID code within the transmitting code with the reference code stored in the reference code storing unit 83, and in the event that a match between the ID code and the reference code is confirmed, the collation is performed between the function code within the transmitting code and the function code stored in the function code storing unit 84. The control signal generating unit 85 generate control signals corresponding to the function code matched by collation. The control signal is supplied to the corresponding controlled mechanism of the vehicle, such as the door for example, and the door is locked or unlocked.
In this case, the ID code appropriated to each portable transmitter 70 in the known keyless entry device is stored in the ID code storing unit 74 of the portable transmitter 70 at the time of manufacturing and is unique to the portable transmitter 70, and the reference code stored in the reference code storing unit 83 of the receiver 80 is stored as the reference code by extracting the ID code transmitted from the portable transmitter 70 and writing the extracted ID code to the reference code storing unit 83.
Generally, users using a keyless entry device prefer that there is no compatibility between the portable transmitter 70 of the user and the portable transmitter 70 of others, so the ID code of the portable transmitter 70 of the user must differ from the ID code of the portable transmitter 70 of others.
One problem is that the portable transmitter 70 of the known keyless entry device requires an ID code writing device, since ID codes which differ for each vehicle are written to the ID code storing units 74 by the manufacturer at the time of manufacturing. An additional problem is that ID code management becomes complicated.